Cognitive
Examining the cognitive value of a virtual learning environment is very difficult, as there are many other factors which correlate to learning, such as the ones described above. Particularly, distraction, fatigue, and cognitive overhead in mastering the interface influence the outcome. The classroom studies provide good examples of a situation in which all the above took place, and where one cannot derive any conclusions about conceptual learning. The results from the case studies are more promising, as the studies were more focused, prolonged, and with less noise and disorder.

However, even in the case studies, little can be concluded as far as learning is concerned. Confidence in using the interface does not necessarily signify understanding of the subject matter. One of the boys, for example, who reported playing many hours of video games per week, learned the interface very quickly and easily and had very good navigation and picking skills. After interacting with VR for about 40 minutes he was interviewed. During the interview and his post-study questions it was revealed that he had not perceived the effects of the sun and the rain on the plants, nor the function of the umbrellas and sunglasses. This was consistent with his pre-study test, which showed little knowledge of gardening concepts.

To simplify the understanding of the children's knowledge before and after the virtual experience, their responses were grouped into categories.

For the pre-study test, three categories were devised according to the children's understanding of simple ecological relationships. The first category included the responses that displayed a very good understanding of gardening concepts: the plants need water and sunlight (i.e. good temperature), and good soil to grow, they wilt or look brown when they are sick, they wilt if they get too much water and dry out when they get too much sun, and the weeds need to be pulled out. About 12\% of the subjects answered in this way. They were also the ones ranked high in reading/writing skills by the teachers. The second category included most of the above answers except for a few misconceptions (e.g. water is good but sunlight is bad for plants). 42\% of the children's answers fit into this category. The third category included 44\% of the responses, where more than one question included a ``don't know'' response or a wrong answer (such as ``the plants grow down'' when they get sunlight, or that weeds need to be planted and watered). Finally, one child could not answer most of the questions.

The answers to the post-study questions were grouped into categories based on the children's understanding of the NICE model: the plants display umbrellas when they receive too much water and sunglasses when there's too much sun, while the weeds are recycled in the compost heap. The responses here were more difficult to categorize, as many children had trouble synthesizing their learning during post-testing, due to fatigue or excitement, while others misunderstood the questions and answered in the same way as in the pre-test, not understanding that the post-questions pertained to the NICE garden in particular.

Approximately 17 children (35\%) understood, for the most part, the NICE model. Of these 17, 13 were drivers, and all had done well in their pre-study questions. This shows that most of the leaders, children that were actively engaged in the task, understood the model of the NICE garden, whereas only a few of the other children perceived it. Approximately 45\% of the children simply answered ``they grew'' to the questions ``what happenned when you put the rain over the plants'' and ``what happened when you put the sun over the plants''. Five kids answered that they did not know or see what happened while six kids were tired and did not answer at all.

Pedagogical

The children acted naturally while in NICE, just as they would have at a playground. They played, argued, listened, spoke loudly, and even rested. Very few were curious about the technology, excepting a girl who exclaimed that the screens were made of paper. The presence of ``the computer'' was not generally perceived by the children throughout the sessions. As one child put it, ``I thought we were going to play with a computer, but this was different''. This indicates that perhaps virtual reality can provide a natural medium for teaching, once technical and technology-specific problems are resolved.

Although children in these studies participated in the VR session longer than in any other educational VR study, it appears that this was not an important factor in the facilitation of learning. We must agree, however, with Dede (1996) who reports that spreading lessons over multiple VR sessions appears to be more effective than covering many topics in a single session, as we attempted to do in our studies. Reviews and post-tests from their studies demonstrated that students were better able to retain and integrate information over multiple lessons. This is usually the case in school-based learning as well as being the main concept of life-long learning.

With respect to their pedagogical function in the NICE studies, collaboration and the narrative are explored further in the following sections.

Collaboration
The classroom studies were set up to encourage intra-group collaboration and inter-group competition, to ensure that each group had an incentive to focus on the task of creating a tended garden. However, none of these forms of cooperation occured. After each group was split, one sybgroup to go to the CAVE and the other to the ImmersaDesk, the children had to be continuously reminded by the teacher-avatar that they were still one group working on a common goal in the same garden. Most children, however, continued not to perceive this and regarded the other (remote) half of their group as their competitors. There were multiple instances of the two drivers fighting over who would grab the raincloud, and children from one location yelling at the ones in the other location to step out of ``their'' garden. As far as the classrooms were concerned, competition contributed to the excitement of the children in the group, but kept them off-task and distracted them for nearly the entirety of the experience. Some of the groups even displayed a form of intra-group competition between the leader and other members. This related mainly to the control of the wand. Notable is the case of one girl who caused constant conflict because she was not the one chosen to be in control. The intent during these studies was to have only one child in each group control the wand. Our rationale for this was efficiency: it is easier and quicker to teach one subject than all; it is more efficient for one to control while others direct the activity, and it avoids fighting over who will do it.

On the other hand, this efficiency gain might not be helpful in terms of advancing all the students' learning. In the case of the other students, it was evident that the control over their learning and their experience was in the hands of the leader of the group. It was hoped that, in this way, the students would be able to pay more attention to the subject matter by leaving the control of the learning situation to the leader. For the child controlling, we supposed that this would not be an advantage, as it could lead to less attention to the subject matter and more to the task of controlling. As noted previously, the opposite was observed in these studies: the leader paid more attention to the subject than the other, less active members of the group.

Contrary to the classroom's behavior, the pairs of children in the case studies displayed excellent collaboration and no competition. In most cases, on-task communication was observed and there was general agreement on actions. Based on these observations, issues regarding the selection and number of members in a group must be taken into account for a successful collaborative combination.

For both the classroom as well as the case studies, the teacher-avatar seemed to serve a helpful purpose, especially for giving the kids tips and keeping them on task. In terms of the classroom children, of course, the teacher-avatar consumed most of her time attempting to keep order - not unlike a real classroom.

The Story
The system's visual output (the narrative WWW page) was shown to each group during the interview. Each group was represented in the story by the avatar of the leader. Some children did not understand this until it was explained to them while showing them the narrative. Most were fascinated by the pictorial representations of the characters and vegetables and remembered what they were doing by looking at the story. It is believed that the iconic representation was helpful in giving the groups a general overview of their actions and is worthy of further exploration. An unanticipated function of the story was its use as a spelling aid by two children from different groups. When completing their questions, they asked to look at the WWW page to find the spelling of certain object names.